Method of forming designs in relief



y 1951 T. J. D. FULLER, JR 2,555,077

METHOD OF FORMING DESIGNS IN RELIEF Filed Nov. 4, 1948 3 Sheets-Sheet 1 May 29, 1951 'r. J. D. FULLER, JR

METHOD OF FORMING naszcms IN RELIEF 3 Sheets-Sheet 2 Filed Nov. 4, 1948 l fi .lzzlzeni'or:

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Patented May 29, 1951 UNITED STATES PATENT OFFICE 2 Claims.

My invention relates to a method of forming designs in relief in friable materials, such as glass, when used in articles such as signs, plaques, mirrors and the like.

It has heretofore been common to cover glass plates with masks of resist material and sand-- blast the exposed portions to the required depth. In accordance with the proccss'of the present invention, sandblasted products can be made with smoother surfaces, and a pleasing number of color effects can be easily and inexpensively ob tained. Y

The nature of the invention may best be'understood from the following description in conjunction with the accompanying drawings, in which Fig. 1 is a top plan view of a part of a glass plate bearing a fanciful design;

Fig. 2 is a vertical section taken through the middle of said plate;

Fig. 3 is an enlarged section of the portion indicated by lines 33 in Fig. 2.

Figs. 4 to 9 are views in vertical section of a laminated structure showing progressively the operations performed in the process of the invention.

In the drawings, and particularly Figs. 1 to 3 inclusive, a sheet, plate or block I of glass or other backing material is shown provided with a design in relief 2 in which different portions are at different levels, and usually in contrasting colors. Thus the sheet I may be black, the portions 3 may be mirrored crystal glass, the star ring 4 may be a painted indentation in the material of which portion 3 is formed, and the circular part 5 may be of flashed ruby glass in which lettering 6 may appear, either by showing through from below (as shown) or by being etched in the top surface.

As shown in Figs. 2 and 3, each design is made from a laminated structure, portions of which are removed in making the design. Each layer is bonded to the next by an adhesive film or sheet I, which, when exposed by removal of a layer, can also serve as a resist material.

The method of the invention will be described in conjunction with Figs. 4 to 9 inclusive. According to this method, a laminated structure is first built up of several layers of glass, phenolic resins or other friable material which may be sandblasted. In between each layer is placed a sheet or film of an adhesive. I prefer to use a thermoplastic material such as vinyl butyral which is capable of permanently bonding layers of glass under heat and pressure, and which is resistant to sandblasting when cool and hard. There may be as many layers as required by the design to be formed. The block of layers of material or sandwich is then pressed under suitable heat in an autoclave. When cooled, the layers of friable material are held firmly bonded together by the plastic. For the purpose of illustration, it will be assumed that the layer [6 indicated in Figs. 4 to 9 (which later becomes sheet 1 of the finished design) is a sheet of black glass. This layer, which is not subsequently sandblasted in the particular design shown, need not for that design be a friable material however. On this layer is placed a film H of vinyl butyral resin which, although greatly enlarged for purposes of illustration, may be only .015 inch thick in practice. Over this is placed a sheet of glass I? which is in turn covered with the plastic layer l3. Topmost is a layer of colored glass M which may be plain, or decorated as by the lettering 6 shown in Figs. 1 to 3. The layers of glass will usually be contrasting; for example, the second layer may be mirrored crystal, and the last layer ruby. The finished structure is illustrated by Fig. 4. The top layer it is now covered with a sandblast stencil 28 having an appropriate design (Fig. 5) and the sandwich is sandblasted until it is worn away and pulverized in all uncovered regions. In Fig. 6, the remaining portions are indicated at 2|. (In Fig. 1 of the drawings, this step would result in the round portion 5, the edge H of which is somewhat roughened or frosted by the blasting.) The layer I2 is unimpaired, as it is protected by the film l3. This film is now out with a stencil knife as indicated at 23 (Fig. 7) to form a new pattern or design, and the exposed portions of the next layer [2 are sandblasted. If desired, the blasting may be stopped before the next film H is reached, to form a design like that of the star-ring 4 shown in Figs. 1 and 2, and the bottom and sides of the area can be coated with paint. At other places, however, as indicated by Fig. 8, the blasting is continued until the film H is reached, leaving the design portions 24. In the illustrative design of Fig. 1, this was done to form the crystal wavy portion 3 on a black background. The film H prevents the blast from roughening or penetrating the first layer it, which, on stripping the exposed portion of the film H as indicated at 25 in Fig. 9, has a fine, smooth finish. The edges of the crystal glass may be painted or left frosted.

The plastic film is preferably transparent for most uses and, after adhesion, is virtually invisible in the regions of the sandwich where the layers of material are not removed. It takes the appearance of whatever material it adheres to. Thus the plastic adhesive is both a permanent invisible binder in places and a temporary binder and a resist material in others. It is partially removed in regions where further blasting is desired, and So serves as a stencil, the uncovered portions of which may if desired be easily removed after blasting is finished.

The resulting product is strong and attractive. The designed parts are more durable, as they are firmly held during formation of the design, thus avoiding cracking and breaking. Very slender, delicate-appearing, designs can be formed. The designs are formed in sharp relief with smooth horizontal portions, as the design can be a succession of strata with smooth surfaces. The use of the laminated structure also permits a considerable variety of treatment not easily possible when forming designs on separate pieces and afterward joining the pieces.

Throughout the description, the word friable is used to indicate a material like glass in that it can be pulverized by sandblasting. Other transparent plastics which can be used as adhesives, resist materials and stencils are polystyrene, methyl and butyl methacrylate, cellulose acetate and cellulose nitrate, all suitably plasticized. None of these materials is as good, however, as the vinyl butyral. The adhesive layer may be formed of a thin sheet of plastic coated on both sides with a film of adhesive. In all cases the bond must be substantially permanent in the uncut regions, while in the cutout regions the adhesive layer can be removed.

I claim:

1. The method of forming designs in relief by sandblasting which includes the steps of forming a laminated structure in which at least one layer of a sandblast resistant plastic capable of forming an adhesive bond is interposed between layers of friable material, masking a portion of the structure, and removing by sandblasting the unmasked portion of the structure to the level of the plastic layer.

2. The method of forming designs in relief which includes the steps of interposing an adhesive forming sandblast resistant plastic between layers of friable material, pressing and heating the layers until an integral structure is formed, sandblasting portions of the friable material to the depth permitted by the layer of plastic material, cutting away a portion of the plastic material, and sandblasting the friable material exposed by said cutting.

THOMAS J. D. FULLER, JR.

REFERENCES CITED The following references are of record in the 25 file of this patent:

UNITED STATES PATENTS 

